On the list of the most pressing dangers that threaten our civilization, the expansion of the universe is somewhere at the very end. However, according to Dan Hooper, a physicist at Fermilab (USA), she should not be overlooked. And he offers his own solution to this problem.
Humanity cannot study or at least somehow influence what happens outside the cosmological horizon, that is, the maximum distance that light travels to us during the existence of the Universe. Other stars, galaxies, even civilizations may exist beyond this horizon, but since light cannot reach us, we will not be able to make contact with them, writes MIT Technology Review.
But this horizon is changing. Hooper calculated how this would affect us and our neighboring galaxies, which astronomers call the Local Group. There are about 50 of them, and they are gravitationally bound to the Milky Way. Within about the next trillion years, they will merge into a single supergalaxy, which will be home to humanity for the foreseeable future. Billions of years from now, we may even colonize it.
However, the expansion of the Universe is pushing galaxies out of the horizon at an increasing rate. “As a result, in about 100 billion years, all stars outside the Local Group will disappear beyond the cosmic horizon and become not only unobservable, but completely inaccessible,” says Hooper.
And Hooper found a way out of the situation that our distant descendants can get into. But first, a little background. In the 1960s, the legendary physicist Freeman Dyson suggested that advanced civilizations would be able to harness the energy of the stars by building huge spheres around them. Scientists have developed this idea in novels, and astronomers have looked for traces of radiation from such structures, so far to no avail.
Hooper hypothesized that a highly advanced civilization could build a sphere that emits residual radiation in a specific direction. This radiation accelerates the sphere - and the star inside - and directs it in the opposite direction of expansion. So, all the necessary stars could be kept inside the horizon.
Hooper considers stars of the mass of the Sun ideal for such a maneuver, because they have sufficient energy and at the same time they are easier to control than small ones.
Hooper's prediction is measurable. If there are already civilizations that have thought of such technology, astronomers will be able to notice them. "Such civilizations will look like a region of up to several tenths of a megaparsec radius, in which all or most of the stars are lighter than two solar masses, surrounded by Dyson spheres," the physicist says.
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Georgy Golovanov